Switch



SWITCH Filed July 23, 1956 Patented Dec. 26, 1939 SWITCH Elmer n.

Gamewell Company,

Little, Needham, Mass minor to The Newton Center, Mara, a

corporation of Massachusetts Application July 23, 1936. serial No. 92,158

2Claims.

The present invention relates to switches and more particularly to. so-called cam switches in which one or more movable contacts are operated by a cam or similar device.

One object of the present invention is to provide a cam switchhaving provision forselective operation of contacts under either looking or non-locking conditions, and arranged to prevent overrunning of the switch parts upon a restoring movement to normal position.

Another object is to provide a contact group assembly which is attachable to and removable from the switch frame as a unitary structure, without disturbing the adjustment of the contacts.

with these and other objects in view, as will hereinafter appear, the present invention comprises the switch hereinafter described and particularly defined in the claims.

In the accompanying drawing illustrating what is now considered the preferred form of the invention, Fig. 1 is a plan view of the switch; Fig. 2 is a sectional elevation on line 2-2 of Fig. 1; Fig. 3 is a rear elevation; and Fig. 4 is a front elevation of the switch. I

The switch illustrated in the drawing comprises a metal frame 5, U-shaped in plan, the side arms of which are maintained in proper spaced relation by spacers or struts indicated at B and I0, the struts being provided with ears extending through suitable slots in the frame and riveted over. Pivoted at the front end of the frame is a cam plate l2 of generally circular form. The cam plate is mounted on a hub l4 which is pressed on ashaft IS. The shaft with its assembled cam plate and hub is free to oscillate in the side walls of the frame. The hub is provided at one side with an enlarged portion l8 between one side of the cam plate and the frame to act as a spacer and to maintain the cam plate in a proper position.- The front of the plate l2 extends through a vertical slot in the front of the frame and carries at its outer end a handle 20. Near the rear of the plate and on opposite sides of the median line are mounted cam rollers 22 of insulating material. The rollers are supported on shafts 24 which are pressed in the plate l2. As shown in Figs. 1 and 2 the rollers are four in number, there being onecn each side of the plate both above and below the median line. The rollers are constructed to operate the movable contacts of four switch groups.

.The switch members include four groups of contacts, two above and two below the median line of the switch. As shown in Fig. 2 the two (01. zoo-1) upper groups are of the locking type and the two lower groups are of the non-locking type, that is to say, upon operation of the switch with respect to the upper groups, the plate I2 is locked until manually restored, whereas when the switch 5 is operated on the lower groups it is not, looked but immediately returns to normal position upon release of the switch handle. The upper or locking groups each comprise fixed contact springs 25 and 28 and an intermediate or mov- 1 able contact spring 30, the front end of which is bent upwardly as indicated at 32. Each of the lower groups comprises fixed contact springs 34 and 35 and a straight intermediate or movable contact spring 38. The ends of the movable contact springs 30 and 38 lie adjacent to the respective actuating rollers 22.

The contact springs of the several groups are mounted between blocks of insulating material 40. The four groups are mounted on metal blocks or plates 42 which extend horizontally between the arms of the frame at the rear thereof. Between the blocks 42 is a spacer plate 44 of the general shape indicated in dotted lines in Fig. l. The contact groups are mounted in place on the blocks 42 by screws 46 which extend through suitable openings in the contact springs ,and the blocks, and are insulated from the contact springs by bushings 48. The screws are threaded into tapped plates 50 at the bottom. The entire contact assembly is supported by means of a strap 52 having ears 54 seated in suitable recesses at the ends of the frame. Longitudinal screws 56 extend between the strap 52 and the strut Hi, the latter being tapped to receive the screws. The spacer plate 44' is of a thickness approximately equal to the diameter of. the screws and, as shown-in Fig. 1, it lies between the screws, its corners being cut out to partially surround the insulatingbushings 48. The entire contact assembly therefore is removable and attachable as a unit. This is an important feature since it permits inspection of the contacts without disturbing their adjustment.

The cam plate l2 cooperates with a detent 4 plunger 58 to hold the plate normally in the position shown in Fig. 2. The plate has a deep angular notch 60 in which the end of the plunger is normally seated. The plunger is mounted to reciprocate in openings in the struts B and I0 50 and is normally urged in a forward direction by a coil spring 6| which bears at the rear against the strut l0 and at the forward end against a washer 62 held in place on the plunger by any suitable means such as a cotter pin. Immediately in the rear of the plunger. I. the blocks 42 are recessed as indicated at M to permit rearward movement of the plunger.

The cam plate on both sides of the notch II is provided with inclined surfaces 04 at a axis of the cam plate.

The cam plate is provided with openings to reor the other.

When the handle 20 is pressed downwardly to turn the cam plate To operate the lower contact groups the handle is moved upwardly, or counter-clockwise. The pin 12 strikes the front wall of the casing at about the time the end of the detent plunger is between the two non-locking condition, and upon release of the handle the switch is immediately restored to its original position.

An important feature resides in the fact that switch cannot result in ovcrrunning, which might result in op- The danger of According to the present invention, the surfaces 64 serve to guide the plunger position.

The switch contact detent-retaining surfaces from said reentrant surfaces, a spring detent normally received in the notch and adapted to be guided into the notch 

